模拟循环冷却系统黄铜管的腐蚀电化学

用研制的黄铜管腐蚀监测传感器对模拟循环冷却系统的黄铜管进行了电化学阻抗谱和电化学噪声测试.电化学阻抗谱测试结果表明,缓蚀剂能够在金属表面上形成保护性膜层抑制腐蚀过程.流速提高时溶液中氧的扩散速度提高,使缓蚀剂在HAl77-2管表面上的成膜作用加强,腐蚀速度降低.电化学噪声测试结果表明,提高流速对HSn70-1管局部腐蚀敏感性影响不大,而HAl77-2管在较高流速下局部腐蚀敏感性提高,表明电化学噪声能用于循环冷却系统黄铜管的腐蚀监测.流速对逆水流方向传感器的影响大于顺水流方向,因此实际应用时传感器应顺水流方向放置,以减小流速的影响.研究结果表明,所研制的传感器适用于动态条件下黄铜管的电化学测试.     

利用电化学阻抗谱和电化学噪声分析薄有机涂层的腐蚀过程

电化学阻抗谱与电化学噪声是方便、有效的监测有机涂层腐蚀破坏的测试技术,EIS数据能够反映出涂层破坏机制的变化,而电化学噪声数据处理简单.本实验在一个改进的电解池中对同一涂层同时进行电化学阻抗谱和电化学噪声的监测,结果发现:对于薄的聚氨酯和环氧/聚酰胺涂层,谱噪声电阻R0/sn(f→0)与噪声电阻Rn在涂层腐蚀破坏过程中的发展趋势基本一致,但R0/sn(f→0)小于Rn值;同时,腐蚀反应的极化电阻Rt与噪声电阻Rn的值更接近,变化趋势也基本相同.     

检测涂层防护性能的电化学方法

电化学方法测试涂层防护性能较之于常规的方法如场地曝晒、盐雾试验、盐水浸泡、干湿循环试验等有许多优点:测试方便快捷,破坏少,获得与涂层防护性能相关的直接信息量大,同时能对金属的腐蚀机理及涂层失效行为进行更深入的研究.本文参考近年来国内外相关文献,对检测涂层防护性能的电化学方法做了总结,综述了直流法、电化学阻抗谱法、电化学噪声法、扫描开尔文探针及扫描振动电极等技术在检测涂层防护性能方面的应用.     

电化学噪声技术对不锈钢表面局部腐蚀监测的应用进展

本文介绍了电化学噪声技术的原理及分析方法,利用恒电流极化在不锈钢表面制造局部腐蚀坑,通过电化学噪声技术对不锈钢表面局部腐蚀进行监测,并通过微观形貌、线性极化、电化学阻抗对电化学噪声的监测效果进行验证.结果表明,采用电化学噪声技术能够有效的对局部腐蚀进行监测,且微观形貌、线性极化与电化学交流阻抗的表征测试结果均与电化学噪...     

EIS法研究3种配套涂层体系的腐蚀电化学行为

采用电化学阻抗谱(EIS)研究了由水性无机富锌底漆、环氧中间漆和氯化橡胶面漆3种涂料配套而成的3种不同涂层体系在3.5%NaCl溶液中的电化学腐蚀行为,考察了氯化橡胶面漆、水性无机富锌底漆／氯化橡胶面漆、水性无机富锌底漆／环氧中间漆／氯化橡胶面漆这3种涂层体系的阻抗谱在浸泡过程中的演化并据此比较了3种涂层体系的防护性能。结果表明,两涂层体系的防护性能比单涂层的还要差,三复合涂层体系的防护性能最好。根据涂层腐蚀电化学阻抗谱特征推测,中间漆在三复合涂层体系中起到了使底漆和面漆结合更加紧密的桥梁作用。     

海洋微生物介质中碳钢腐蚀电化学行为研究

采用电化学阻抗谱、极化曲线等测试技术,研究了碳钢在不同培养周期下的海水微生物介质中的腐蚀行为.结果表明,海水中未经纯化的微生物使碳钢电极的腐蚀电位负移;电极表面完整均匀微生物膜的存在不改变阴极的极化类型和控制步浇骤,只对阳极腐蚀过程起加速作用;电化学阻抗谱证实,在有菌存在的条件下,电极的阻抗值下降,微生物的存在会加速碳钢电极的腐蚀作用.     

电化学技术在汽车腐蚀分析中的应用

指出传统车身腐蚀分析时凭主观判断等级的局限性,认为电化学技术可以从更加微观和客观的角度对腐蚀行为作出分析.通过电化学经典的极化曲线和阻抗谱,可以对车身腐蚀机理进行解释.阐明了电化学技术在汽车腐蚀分析中的使用价值和应用前景.     

炼厂柴油罐腐蚀的预防

炼油厂的柴油罐腐蚀具备局部性、隐蔽性,发生穿孔后处理比较麻烦。以抚顺石化储运厂柴油罐防腐工作为例,介绍了柴油罐腐蚀的影响因素、腐蚀的特点及分析和预防的办法。     

基于声发射检测的罐底腐蚀安全评估

常压储罐一旦发生泄漏,往往会造成人员伤亡、财产损失和环境污染等严重后果,因此对于储罐的安全评估尤为重要。现有的检测方法存在耗时长、易漏检、经济效益低等不足之处。以实例说明了声发射在线检测技术应用于罐底腐蚀检测的高可靠性与便捷性;解释了机械噪声、环境噪声以及电磁噪声形成的原因,并提出了相应的滤除方法;描述了基于声发射检测的罐底腐蚀安全评估的过程与评价依据,并进行评估。     

氧化锆氧传感器铂电极的制备与表征

采用陶瓷注射成型技术制备了氧化锆(ZrO2)固体电解质基体,在烧成的ZrO2基体上涂制铂(Pt)电极浆料,将电极在不同温度下烧结.用扫描电镜表征所制备的Pt电极和进行时效实验电极表面的微观形貌,结果表明:电极烧结温度和时效时间对电极微观形貌影响很大.用电化学阻抗谱研究了Pt电极的电化学性能,结果显示:所制备的Pt电极显示出优良的电化学催化性能.     

Investigation of strength degradation of adhesive-bonded aluminum joints exposed to corrosive environment using electrochemical methods

Interfacial corrosion is responsible for the strength degradation of adhesive-bonded aluminum joints (ABJs) exposed to corrosive environment. In this study, electrochemical noise and electrochemical impedance spectroscopy (EIS) measurements were performed on the aluminum alloy X610-T4PD covered with adhesive (ACA) to understand the interfacial corrosion. And environmental simulation tests (i.e. neutral salt spray (NSS) and hot humidity environment) for ABJ were carried out to investigate the joint strength degradation. Test results indicated that the variations of current and potential in the EN measurement were closely related to the initiation of corrosion in the samples. The Nyquist plots in the EIS measurement for various immersion times showed that the corrosion of ACA accelerated after about 140 h. Furthermore, a linear relationship between the residual strength of ABJ exposed to NSS and the reciprocal of interfacial corrosion resistance (R_t) of ACA was found, which was verified by ABJ exposed to hot humidity environment.     

电化学阻抗谱在电沉积研究中的应用(一)

介绍了电化学阻抗谱在各种金属及合金的电沉积研究中的应用。文章分3期连载。第一部分介绍了电化学阻抗谱的基础知识,包括复数、复阻抗的概念,以及在各种常见条件下电解池的等效电路图。     

电化学合成重铬酸钠阳极稳态极化及交流阻抗法研究

针对重铬酸钠传统生产技术存在问题,提出电化学合成重铬酸钠的绿色新技术,阳极为自制钛基多元金属氧化物复合电极,所用阳极液为铬酸钠水溶液.阳极既是电催化合成过程的催化剂,又是电催化反应进行的场所.根据电催化合成重铬酸钠体系的特点,运用稳态极化曲线和交流阻抗技术研究了阳极反应动力学及电化学行为.实验测得阳极反应活化能等电极反...     

电化学阻抗谱在电沉积研究中的应用(二)

文章的第二部分介绍了电化学阻抗谱在金属(包括锌、铜、镍、铅、铬)及合金(锌–铁、钴–镍、镍–钼)电沉积研究中的应用。     

Resistance of the Polypyrrole/Polyimide Composite by Electrochemical Impedance Spectroscopy

Electrically conducting polymers are promising for applications in polymer based charge storage devices and for membrane applications. Composing polypyrrole with polyimide improves mechanical properties of polypyrrole and affects the electrochemical properties of the composite. In this paper resistance to ion flow of pure polyimide and of the polypyrrole/polyimide composite were studied by electrochemical impedance spectroscopy, comparatively, as a function of applied potentials and of amount of polypyrrole. Electron scanning microscopy and surface mapping were used for surface characterization. Observed behavior was explained with electroactivity of the components of the composite. Conclusions about the effect of polypyrrole on the structure and resistance were made.     

Inhibition Effects of a Synthesized Novel 4-Aminoantipyrine Derivative on the Corrosion of Mild Steel in Hydrochloric Acid Solution together with Quantum Chemical Studies

1,5-Dimethyl-4-((2-methylbenzylidene)amino)-2-phenyl-1H-pyrazol-3(2H)-one (DMPO) was synthesized to be evaluated as a corrosion inhibitor. The corrosion inhibitory effects of DMPO on mild steel in 1.0 M HCl were investigated using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, open circuit potential (OCP) and electrochemical frequency modulation (EFM). The results showed that DMPO inhibited mild steel corrosion in acid solution and indicated that the inhibition efficiency increased with increasing inhibitor concentration. Changes in the impedance parameters suggested an adsorption of DMPO onto the mild steel surface, leading to the formation of protective films. The novel synthesized corrosion inhibitor was characterized using UV-Vis, FT-IR and NMR spectral analyses. Electronic properties such as highest occupied molecular orbital energy, lowest unoccupied molecular orbital energy (EHOMO and ELUMO, respectively) and dipole moment (μ) were calculated and discussed. The results showed that the corrosion inhibition efficiency increased with an increase in the EHOMO values but with a decrease in the ELUMO value.     

Effects of Proton-Exchange Membrane Fuel-Cell Operating Conditions On Charge Transfer Resistances Measured by Electrochemical Impedance Spectroscopy

Abstract

Proton-exchange-membrane fuel cells (PEMFC) are highly dependent on operating conditions, such as humidity and temperature. This study employs electrochemical impedance spectroscopy (EIS) to measure the effects of operating parameters on internal proton and electron transport resistance mechanisms in the PEMFC. Current-density experiments have been performed to measure the power production in a 25 cm² Nafion 117 PEMFC at varying operating conditions. These experiments have shown that low humidity and low temperature contribute to decreased power production. EIS is currently employed to provide a better understanding of the mechanisms involved in power production by calculating the specific resistances at various regions in the PEMFC. Experiments are performed at temperatures ranging from 30 to 50°C, feed humidities from 20 to 98%, and air stoichiometric ratios from 1.33 to 2.67. In all experiments, the hydrogen feed stoichiometric ratio was approximately 4.0. EIS is used to identify which transport steps limit the power production of the PEMFC over these ranges of conditions. The experimental data are analyzed via comparison to equivalent circuit models (ECMs), a technique that uses an electrical circuit to represent the electrochemical and transport properties of the PEMFC. These studies will aid in designing fuel cells that are more tolerant to wide-ranging operating conditions. In addition, optimal operating conditions for PEMFC operation can be identified.